Caption: A map shows the location of the August 24, 2014 earthquake just south of Napa, California. ShakeMaps provide near-real-time maps of ground motion and shaking intensity following significant earthquakes. The South Napa earthquake was very well recorded and produced a number of strong ground motion recordings that are of considerable interest to the engineering community. At 6.0 on the moment magnitude scale and with a maximum Mercalli intensity of VIII ( Severe ), the event was the largest in the San Francisco … Inspection of the buildings after the earthquake yielded 100+ red-tagged structures, meaning immediate rehabitation is too dangerous. Email. The red star is the location of the mainshock. The SAFZ is not a simple, single fault, but rather a complex collection of smaller fault segments that collectively accommodate the horizontal movement between the North American Plate and the Pacific Plate. One year ago, the largest earthquake in over 25 years hit the San Francisco Bay Area, causing significant damage in California’s famous Napa Valley. Damage to structures decreased with distance from the rupture. To assist the Federal Emergency Management Agency (FEMA) with response and recovery after the quake, the USGS and its scientific partners prepared a report with details of fault afterslip, shaking and damage in the city of Napa downtown area, and fault hazards of the West Napa Fault System, as well as associated geospatial information and imagery. A smaller magnitude 5.0 earthquake on the same fault had damaged the city of Napa in 2000. (Public domain.). The event was the largest in the San Francisco Bay Area since the 1989 Loma Prieta earthquake. It was the biggest temblor to hit the Bay Area since the M6.9 Loma Prieta earthquake of 1989. The highest intensities were MMI VII-VIII in the city of Napa and extending a littler farther north. Some residents noticed a difference in the amount of water being discharged from natural springs. Or, try our Real-time Notifications, Feeds, and Web Services . The same could be said for the tornados in the midwest and south, and hurricanes in the southeast coastal areas. For further details, see Groundwater Effects from Earthquakes. Afterslip is a slow movement on the fault, and it is yet unclear whether it is associated with, or independent of, the aftershocks. The magnitude 6.0 earthquake occurred early in the morning on August 24, 2014, on the West Napa Fault. Seismicity in the Napa area 1973-2015, all magnitudes. The moderate earthquake that struck California’s Napa Valley on Sunday collapsed older buildings, sparked fires and caused scores of injuries. the commercial buildings were pre-1950 masonry and had not been built to current code standards or retrofit. There was no evidence for the shaking being strongly amplified in any particular pockets of the downtown area. The earthquake was unusual for the length of surface rupture (8 miles), the amount of surface slip (up to 18 inches), and the large afterslip that followed the earthquake (up to 14 inches). The only other noteworthy earthquake in the Napa area in the recent past (since 1973) was the M4.9 Yountville earthquake on September 3, 2000. Ultimately 41,000+ citizens shared their experiences, with the farthest felt report 300 km (186 mi) to the east in Reno, NV. The 24 August 2014 Mw 6.0 South Napa earthquake occurred on … Twitter. The crosses and letters indicated cross-sections not shown in this image. In addition, a M3.0 earthquake occurred on August 5, 2014, 19 days before the M6.0, which, in retrospect, some scientists/seismologists might consider a foreshock. The relative motion on this fault is not well known but thought to be about 1 mm/yr (0.04 in/yr). Rivers and streams in the area were flowing at record lows at the time of the quake because of the continuing drought, so when water began to flow again in some previously dry surrounding creeks and streams in the aftermath of the South Napa Earthquake, it prompted many nearby residents to scratch their heads. Engineers and scientists determined that the worst-damaged buildings resulted from a combination of: The South Napa earthquake caused this ground surface rupture running through a viineyard near Buhman Road, Napa Valley, California. Yountville, Vallejo, and American Canyon were also damaged. Afterslip forecast hazard map of the Browns Valley neighborhood and surrounding area in Napa, Calif. The South Napa Earthquake provided a valuable reminder to engineers and the public of what they should expect from time to time when they live in earthquake country. The shaking causes the shifting of below-surface features that may temporarily (and sometimes permanently) change the flow from a spring or even stop the flow. The length of the rupture was about 12.5 km (8 mi), and scientists measured up to 46 cm (18 in) of slip. Existing fault maps show that the Franklin Fault extends southward to the Calaveras Fault zone and the West Napa Fault extends north of the seismic array. With each earthquake experienced, scientists learn more about the hazards, and how the natural and built environment will respond. Our better scientific understanding of the 2014 earthquake sheds light on the nature of earthquake faults and hazards in the region, and will enable communities to be better prepared and better able to withstand the next earthquake. The change occurred within 1 hour after earthquake, but the discharge amount returned to normal within a few days. The sharp rise starting on August 24 reflects an increased streamflow due to the South Napa Earthquake. (Public domain. The "Did You Feel It?" Copy Link. One year ago, the largest earthquake in over 25 years hit the San Francisco Bay Area, causing significant damage in California’s famous Napa Valley. Over 41,000 people went online to report what they felt during the event. Residents in this area feel small earthquakes often, and they generally pause for a moment and then go back to whatever they were doing. maps compiled from these personal accounts, reflected peak shaking intensities up to a “severe” level, just a little bit less than the “violent” shaking calculated in the instrument-generated ShakeMaps. Cullen 328 Let's discuss it 05:47, 26 August 2014 (UTC) This article in the San Jose Mercury News, published about 80 miles away, specifically mentions that "South Napa Earthquake" is emerging as the accepted name. This lack of ground failure was attributed to the lack of rainfall in the area; a shallower water table would have made the surface material less stable and more prone to ground failure. The numbers of aftershocks following the earthquake was relatively low for an earthquake of this size, and in contrast to other large Californian earthquakes, the aftershock locations do not clearly outline the main fault rupture surface. Also, fault strands that had been mapped prior to this earthquake were not thought to be highly hazardous. LOS ANGELES _ In a land where the mildest rumble elicits an anxious question _ "Did you feel that?" The 6.0-magnitude quake struck at 3:20 … Key Recovery Factors for the August 24, 2014, South Napa Earthquake Hurricane Marie peaked on 8/24 at 21 UTC - about 2 hours from the Peru earthquake. The South Napa earthquake occurred on Sunday, 24 August 2014 at 3.20 am local time at a depth of 10.7 km, having MW 6.0 and causing significant damage to unreinforced masonry (URM) buildings In response to the earthquake, California Earthquake Clearinghouse established a physical clearinghouse location in Napa, CA from August, 24 to August 26, 2014. Geologic Hazards Science Center, Golden, Colorado. The sharp rise starting on August 24 reflects an increased streamflow due to the South Napa Earthquake. The computed instrumental intensities agreed well with those reported by residents. _ having even a few seconds of warning before an earthquake Frequently Asked Questions (FAQs) for Tenants After the 2014 South Napa Earthquake To aid tenants who have been affected by the 2014 South Napa Earthquake. Hydrograph showing stream flow in cubic feet per second on USGS streamgage on Sonoma Creek near Agua Caliente, from about August 23 - September 13, 2014. Almost three years have passed since the 2014 magnitude-6.0 South Napa earthquake. Afterslip causes additional damage to manmade structures, such as roads, but does not release seismic waves and cause shaking. The team comprised a diverse mix of perspectives and backgrounds, including Once fully implemented in the western U.S., the advance warnings of a few seconds up to a minute or more provided by the ShakeAlert system can be enough to slow public transit systems, open fire-house doors, and allow people to “Drop, Cover and Hold On.” Although there were no trains running at 3:20 a.m. when the earthquake happened, the Bay Area Rapid Transit (BART) system’s automated train-stopping system did successfully activate when the warning was received. The earthquake woke people throughout northern California, in cities as far away as Sacramento and Santa Cruz. The following summary is what USGS (and USGS-funded) scientists have learned from the data one year after the earthquake. Results suggest the West Napa Fault and the Franklin Fault (to the southeast) may be continuous at depth. The WNFZ was mapped as a 46-kilometer long segment of subparallel fault traces from Vallejo to Saint Helena, California. This anniversary of the event is a time to look back at what the U.S. Geological Survey and its scientific partners have learned from the South Napa Earthquake. “Did You Feel It?” community intensity map indicating the severity of shaking felt by people in central California during the South Napa Earthquake in 2014. The 2014 South Napa earthquake was the first large earthquake (Mag 6) to occur within the Plate Boundary Observatory GPS network since installation. A strong, 6.0-magnitude earthquake jolted Northern California yesterday (Aug. 24) at 3:20 a.m. local time. The first PAGER Assessment (providing fatality and economic loss impact estimates) was issued 13 minutes after the earthquake, and accurately forecast a low level of human casualties, but significant economic losses in the area. (Josh Edelson/AFP/Getty Images) The drought-induced low water table and dry ground inhibited landslides and liquefaction that can occur during earthquakes of this size, sparing the area greater damage than could have been. the wood-frame houses that were damaged were older ones that had not been retrofit (see links below for retrofitting information). (Public domain.). In addition, airborne and ground-based LIDAR data were collected in areas known to have surface cracks to measure and describe what happened. The first offset measurement was taken the day of the earthquake - about 6 cm (2 in) of right-lateral offset. Pavement buckling and tented sidewalk resulting from compressional forces at north end of main fault rupture, Sandybrook Lane, Napa California. Immediate Impact In a new report, scientists from MIT and elsewhere detail how, even after the earthquake’s main tremors and aftershocks died down, earth beneath the surface was still actively shifting and creeping — albeit much more slowly — for at least four weeks after the main event. When the pressure adjusts and equilibrates with the water table, the flow will often return. The magnitude 6.0 earthquake occurred early in the morning on August 24, 2014, on the West Napa Fault. Initially, the fault afterslip was rapid and extended into at least the southern part of the Browns Valley neighborhood in the city of Napa. Geographic Names Information System (GNIS), Mapping, Remote Sensing, and Geospatial Data. A few homes even shifted off of their foundations, which can be due to the failure of the cripple walls, which drop the floor to the foundation and sometimes allow houses to slide off the foundation. On August 24, 2014, a magnitude-6.0 earthquake occurred in Napa, California. No data point selected. (DYFI) webpage bookmarked, so as soon as the shaking stopped, they started reporting their experience of the shaking on DYFI. Aftershocks during the first week after the mainshock. The seismic hazard posed by the West Napa Fault System is still being evaluated. The South Napa earthquake included a few small segments that ruptured together to produce the M6 earthquake.. USGS Home Contact USGS Search USGS. 2014 South Napa Earthquake Retrospective. The South Napa earthquake along the San Andreas Fault reached 6.0, caused roughly $1 billion in damage, injured 200, killed one and jolted plenty of nerves. For example, the surprising amount of afterslip observed gave scientists a new way to look at and forecast continuing hazards in the weeks to months, after the earthquake occurred. A. Overview. Hydrograph showing stream flow in cubic feet per second on USGS streamgage on Sonoma Creek near Agua Caliente, from about August 23 – September 13, 2014. These events are going to happen regularly. Shallow slipping across the fault, known as afterslip, continued after the mainshock and lasted for several months. The M6.0 South Napa earthquake occurred on August 24, 2014. After the 2014 South Napa Earthquake, approximately half the households in the city of Napa and in western Vallejo that reported an injury stated that the injury occurred dur-ing cleanup activities. After the earthquake, one or more types of traumatic exposure were reported among 27% and 4% of Napa and western Vallejo households, respectively; Ongoing fault movement along the surface rupture, called afterslip, continued for several months, and caused further damage to foundations and structures. Damaged unreinforced masonry building on Main St. in downtown Napa. 1: What does it mean if my apartment building was red, yellow, or green tagged*? These recordings are being used, in part, to better understand the performance of residences and older masonry buildings that have been retrofitted. The 2014 South Napa earthquake occurred in the North San Francisco Bay Area on August 24 at 03:20:44 Pacific Daylight Time. For example, the California Department of Transportation (Caltrans) received an automated report that they could use to determine which bridges and overpasses experienced the greatest level of shaking and were most at risk to damage so they could prioritize inspections. It provides an excellent example for studying crustal strain associated with the earthquake cycle of a strike-slip fault with clear societal relevance. The shaking caused some damage to wood-frame houses and significant damage to some commercial buildings in downtown Napa, including the 1870 courthouse. The three largest were a M3.9 on August 26, a M3.2 a week after the mainshock on August 31, and then a M4.1 10 months later on May 22, 2015. Many California residents have the Did You Feel It? Predictions included broad spectrum events for 8/25/14 at 1413 UTC. (Public domain.). Many others spread out across the Napa Valley and surrounding area to collect additional data such as fault rupture expressed on the ground surface, as well as shaking induced damage to buildings and infrastructure. Older structures tended to experience more damage than more recently built structures Earthquake retrofitting of older structures can help to minimize damage in future earthquakes. Scientists found that some of the fault segments that ruptured on the morning of August 24 had been previously mapped as part of the West Napa fault system, but the rupture also extended northward where no faults had been mapped before. The first ShakeCast was issued 11 minutes after the earthquake. ShakeCast is an application for automating ShakeMap delivery to critical users and for facilitating notification of shaking levels at user-selected facilities. 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